Conventional time domain multiple access (TDMA) satellite communication networks employ multiple radio stations which communicate through an earth satellite repeater by transmitting time-synchronized bursts of radio energy relative to the repeater and which receive a time multiplex composite of bursts containing corresponding modulated information from the repeater. In TDMA operations, multiple ground stations associated with radio signaling nodes transmit bursts of time-concentrated information signals on a shared carrier frequency spectrum and receive the same information signals after repetition by the satellite repeater on a shifted carrier frequency spectrum. Each ground station is assigned a particular time slot in a continuum of recurrent frames for transmission of its bursts and for the reception of its own bursts and the bursts of other stations. The bursts interleave at the satellite in close time formation without overlapping. Each earth station includes connections to incoming digital lines originating from terrestrial sources. These input lines are respectively connected to digital data ports on a satellite communications controller (SCC) at the station.
The basic time assigned speech interpolation technique which the prior art has applied to voice is based upon the transmission station recognizing that the voice level to be transmitted is below a certain threshold and therefore no information is transmitted. The receive side then infers that the voice level was not high enough to justify transmission and therefore inserts background noise for example to the recipient at the destination station. The prior art TASI techniques do not apply to a data stream which is examined for replicated bytes of information and when such replication is recognized, and no data transmitted over the medium, the recipient station infers that replication has taken place and therefore replicates the last stored byte at the receive station.
U.S. Pat. No. 2,963,511 shows a pulse code modulated stream which is followed by run length encoding word and U.S. Pat. No. 2,978,535 discloses a facsimile transmission scheme in which sample sizes of 1, 2, 4 or 8 bits are examined and then a control word sent for run length encoding of a number of bit or byte lengths for which data is to be replicated.
What is needed is an improved technique for reducing the bandwidth necessary to carry out data activity compression in a TDMA satellite communications network.